Technical Field
Embodiments of the invention relate generally to engine air systems. Particular embodiments relate to mitigating condensate collection within exhaust gas recirculating engine air systems.
Discussion of Art
In response to evolving emissions regulations (e.g., Tier 4 and IMO 3), engine manufacturers globally are investing in technologies such as two stage turbocharging, common rail fuel systems, exhaust gas recirculation (“EGR”), selective catalytic reduction (“SCR”), and exhaust gas after-treatment. For example, two stage turbocharging and EGR can be combined for enhanced fuel efficiency and exhaust cleanliness. But under certain ambient conditions, particularly in maritime environs, intake air moisture can condense during turbocharging. This condensate must be removed before reaching the intake manifold, in order to prevent corrosion and other engine damage. Also, when fuel containing sulfur (e.g., marine diesel oil) burns inside the engine combustion chamber, the combustion products include sulfur oxides. Exhaust gas containing sulfur oxides, when mixed with moist intake air via EGR, forms acidic vapors that can condense in the engine. Quantities of acidic condensate depend upon the sulfur content in the fuel as well as the engine operating conditions. Unless removed from the system, the condensed acidic medium will corrode at least the exhaust gas recirculation (EGR) cooler as well as the air intake manifold.
In view of the above, it may be desirable to provide apparatus and methods to passively drain condensate from the charge air system of a diesel engine with the condition that the charge air contains products of diesel combustion exhaust and cannot be vented directly to the local environment.